Conditions InDepth: Hyperthyroidism

Hyperthyroidism, sometimes called thyrotoxicosis, is a condition in which the thyroid gland produces too much thyroid hormone. The thyroid gland is a butterfly-shaped gland in the front of the neck. It produces the hormones thyroxine (T4) and triiodothyronine (T3), which control metabolism. This affects how many calories you burn, how warm you feel, and how much you weigh. These hormones also directly affect the heart, making it beat faster and harder. The thyroid gland also produces the hormone calcitonin, which is involved in regulating the body’s calcium level.

The Thyroid Gland

© 2008 Nucleus Medical Art, Inc.

The most common form of hyperthyroidism is Graves’ disease . Graves’ disease occurs when your own immune system produces antibodies that stimulate the thyroid to overproduce thyroid hormone. Hyperthyroidism can be the result of other conditions as well. Since the thyroid gland is regulated by the pituitary and hypothalamus, hyperthyroidism might be caused by malfunctioning of these two glands. Hyperthyroidism can also result from:

  • Substances secreted by tumors of the thyroid gland, testes, or ovaries (which stimulate the thyroid gland)
  • Inflammation of the thyroid
  • Ingesting too much iodine
  • Self-administered dose of too much thyroid medication

Treatment of hyperthyroidism often leads to the opposite condition, hypothyroidism. This is a condition in which the thyroid gland produces too little thyroid hormone. Long-standing hyperthyroidism can lead to chronic thyroiditis, or inflammation of the thyroid, which can in turn result in hypothyroidism.

It is estimated that 13 million Americans have thyroid disorders, and more than half are undiagnosed. One in 8 women will develop a thyroid disorder in her life, and women are 5 to 8 times more likely than men to have hyperthyroidism or hypothyroidism. Up to 2% of women have Graves’ disease; it is one-tenth as frequent in men. Hyperthyroidism can occur at any age, but most typically it occurs between the ages of 20 to 50. It is rare in children and should be considered as a cause of mental or physical change in the elderly.

What are the risk factors for hyperthyroidism?
What are the symptoms of hyperthyroidism?
How is hyperthyroidism diagnosed?
What are the treatments for hyperthyroidism?
Are there screening tests for hyperthyroidism?
How can I reduce my risk of hyperthyroidism?
What questions should I ask my healthcare provider?
Where can I get more information about hyperthyroidism?

References:

American Association of Clinical Endocrinologists website. Available at: http://www.aace.com/ .

American Medical Women’s Association website. Available at: http://www.amwa-doc.org .

Harrison’s Principles of Internal Medicine. 14th ed. McGraw-Hill;2001.

National Library of Medicine website. Available at: http://www.nlm.nih.gov/ .

Pearce EN. Diagnosis and management of thyrotoxicosis. Brit Med J. 2006;332:1369-1373.



Last reviewed May 2007 by David Juan, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.


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